What is the distance from one point on a wave to an identical point on the adjacent wave?

• A. Frequency
• B. Amplitude
• C. Wavelength
• D. Phase

Answer: (C)

Wavelength is the spatial distance between identical points on consecutive waves. If you pick a crest (or a trough, or any fixed phase point) on one wave, the same point on the next wave is separated by one wavelength. This distance is the repeating spatial period of the wave and links to the wave’s speed and frequency through the relation v = f λ.

Frequency, on the other hand, measures how often the wave repeats per unit time, not how far it travels in space. Amplitude describes how tall the wave is—its maximum displacement—while phase refers to where in its cycle a point lies, or the offset between waves, not the spacing between identical points across waves.

So the distance between identical points on adjacent waves is the wavelength.